[PATCH] D137601: Only hash the start of keys in StringMap

Tue Nov 8 16:08:23 PST 2022

erikdesjardins added a comment.

It may make sense to first/also switch to xxHash (already included here https://github.com/llvm/llvm-project/blob/295861514e0d1e48df2918b630dd692ac27ee0de/llvm/include/llvm/Support/xxhash.h#L45), which should be much faster than DJB, especially for large keys.

OTOH, it appears that some tests depend on `StringMap` iteration order, so updating them as a result of changing the hash function may be painful. For example, https://reviews.llvm.org/D97396 (which attempted to change the seed value) was reverted for that reason.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137601/new/

https://reviews.llvm.org/D137601